Evaporator and refrigeration cycle

ABSTRACT

An evaporator including an evaporator core having a refrigerant inlet and a refrigerant outlet in one side portion thereof, and a connecting member joined to the side portion of the core and having in its interior a refrigerant inlet channel and a refrigerant outlet channel. The connecting member includes first and second plates. The second plate has an inlet channel recessed portion and an outlet channel recessed portion provided, each in the bottom wall thereof, with an inlet pipe connecting opening and an outlet pipe connecting opening, respectively. The first plate has on the outer surface thereof a refrigerant flow smoothing projection projecting toward the inlet pipe connecting opening. Refrigerant flowing into the inlet channel flows along the projection surface, thereby changes its flow direction smoothly and is less likely to produce a turbulent flow. The evaporator is therefore adapted to prevent occurrence of noises due to refrigerant flow.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is an application filed under 35 U.S.C. §111(a)claiming the benefit pursuant to 35 U.S.C. §119(e)(1) of the filing dateof Provisional Applications No. 60/363,244 and No. 60/363,369 both filedMar. 12, 2002 pursuant to 35 U.S.C. §111(b).

TECHNICAL FIELD

The present invention relates to evaporators, for example, for use inmotor vehicle air conditioners, and to motor vehicle air conditionersand like refrigeration cycles comprising the evaporator.

BACKGROUND ART

For example in refrigeration cycles such as motor vehicle airconditioners, noises made by the flow of refrigerant, such as awhistling noise and hissing noise, are produced mainly in condensers orexpansion valves. However, such noises are likely to occur inevaporators depending on the conditions involved in the flow of therefrigerant. Especially in the case of motor vehicle air conditioners,noises released from the evaporator which is provided at a positionrelatively close to the vehicle compartment will be disagreeable to thepassenger.

As means for solving such a problem of noises, already proposed are arefrigerant distributor disposed at a position upstream from theevaporator and having a sound absorbing material incorporated therein(see JP-A No. 10-185363) or a muffler disposed upstream from theevaporator (see JP-A No. 11-325655).

These means use the sound absorbing material or muffler in addition tothe usual components of the refrigeration cycle and will thereforerequire a correspondingly increased cost or additional space forinstallation.

A first object of the present invention is to make it possible toprevent occurrence of noises in an evaporator due to the flow ofrefrigerant in motor vehicle air conditioners or like refrigerationcycles, by contriving the construction of the evaporator itself withoutusing additional means such as a muffler.

Further already known, for example, for use in motor vehicle airconditioners are evaporators which have a multi-pass providing innerpipe inserted in an evaporator core through a refrigerant inlet thereofto provide at least two passes and thereby achieve an improved aircooling effect (see U.S. Pat. No. 5,431,217).

Such evaporators include those which comprise an evaporator core havinga refrigerant inlet and a refrigerant outlet in one side portionthereof, and a connecting member joined to the side portion of theevaporator core and having in its interior a refrigerant inlet channelfor holding the refrigerant inlet in communication with a refrigerantinlet pipe and a refrigerant outlet channel for holding the refrigerantoutlet in communication with a refrigerant outlet pipe (see thepublication of JP-A No. 2000-283603).

When the refrigerant for use in the above evaporator flows into theinner pipe from the refrigerant inlet channel via the refrigerant inlet,the flow of refrigerant changes its course approximately through a rightangle. If the diameter of the inlet channel is excessively larger thanthe inside diameter of the inner pipe, the flow of refrigerant involvesan increased pressure loss, possibly failing to exhibit the contemplatedair cooling performance.

Incidentally, the inner pipe is inserted in the core of the aboveevaporator through the refrigerant inlet, whereas there are someevaporators wherein the inner pipe is inserted in the evaporator corethrough the refrigerant outlet. In this case, the refrigerant flowingout of the inner pipe into the refrigerant outlet channel will changeits course approximately through a right angle. If the diameter of theoutlet channel is excessively greater than the inside diameter of theinner pipe, an increased refrigerant pressure loss will also result toentail impaired cooling performance.

A second object of the present invention is to provide a refrigerationcycle, such as a motor vehicle air conditioner, wherein a multi-passproviding inner pipe is inserted in the evaporator core of theevaporator and which is adapted to reduce the pressure loss to beinvolved in the portion where the refrigerant is introduced into theinner pipe or the portion where the refrigerant is discharged from theinner pipe so as to ensure outstanding air cooling performance.

DISCLOSURE OF THE INVENTION

The present invention provides a first evaporator which comprises anevaporator core having a refrigerant inlet and a refrigerant outlet inone side portion thereof, and a connecting member joined to said oneside portion of the evaporator core and having in its interior arefrigerant inlet channel for holding the refrigerant inlet incommunication with a refrigerant inlet pipe and a refrigerant outletchannel for holding the refrigerant outlet in communication with arefrigerant outlet pipe. The connecting member comprises a first platehaving an inlet communication hole and an outlet communication hole andjoined to said one side portion of the evaporator core so that thecommunication holes communicate with the respective refrigerant inletand outlet, and a second plate having an inlet channel recessed portionand an outlet channel recessed portion and joined to an outer surface ofthe first plate so that the recessed portions are opposed each at oneend thereof to the inlet communication hole and the outlet communicationhole respectively. The other end of the inlet channel recessed portionhas a bottom wall provided with an inlet pipe connecting opening, theother end of the outlet channel recessed portion having a bottom wallprovided with an outlet pipe connecting opening, the refrigerant inletpipe and the refrigerant outlet pipe being connectable to the respectiveconnecting openings by a pipe joint member joined to an outer surface ofthe second plate. The first plate is provided on the outer surfacethereof with a refrigerant flow smoothing projection projecting towardthe inlet pipe connecting opening of the second plate.

A refrigerant subjected to a pressure reduction by an expansion valveand in a gas-liquid two-phase state flows into the refrigerant inletchannel of the connecting member of the evaporator through a refrigerantinlet pipe and the pipe joint member and further through the inlet pipeconnecting opening. The refrigerant flowing in impinges on the outersurface of the first plate opposed to the inlet pipe connecting opening,whereby the refrigerant changes its course approximately though a rightangle to flow down the inlet channel. The refrigerant then flows intothe evaporator core through the refrigerant inlet. If the outer surfaceof the first plate opposed to the inlet pipe connecting opening is flat,the change of direction of the refrigerant flow involves increasedresistance and the flow becomes turbulent, consequently permitting theoperation of the air conditioner or like refrigeration cycle to producenoises. When the first plate is provided on the outer surface thereofwith the refrigerant flow smoothing projection projecting toward theinlet pipe connecting opening of the second plate, the refrigerantflowing into the inlet channel flows along the surface of theprojection, whereby the flow of refrigerant has its course changedsmoothly and is made less likely to become turbulent. The firstevaporator of the invention is therefore operable without producingnoises due to the inflow of the refrigerant.

With the first evaporator of the invention, the center of therefrigerant flow smoothing projection is preferably in coincidence withthe center of the inlet pipe connecting opening.

If the projection is so positioned as stated above, the refrigerantinlet portion exhibits an improved effect to smooth the flow ofrefrigerant due to the presence of the projection, reliably preventingthe occurrence of noises.

With the first evaporator of the invention, the first plate may beprovided on the outer surface thereof with a refrigerant flow smoothingprojection projecting toward the outlet pipe connecting opening, inplace of or in addition to the projection provided at the refrigerantinlet portion.

The noise produced by the flow of refrigerant in the evaporator isgenerally liable to occur at the refrigerant inlet portion as statedabove. However, the flow of refrigerant will become turbulent at therefrigerant outlet portion to produce noise, depending on the conditionsinvolved in the refrigerant flow. When the refrigerant flow smoothingprojection projecting toward the outlet pipe connecting opening isformed on the outer surface of the first plate as described above, therefrigerant flowing down the outlet channel flows along the surface ofthis projection, has its course thereby smoothly changed and becomesless prone to turbulence. This eliminates the noise to be produced bythe outflow of the refrigerant.

With the evaporator described, the center of the refrigerant flowsmoothing projection is also preferably in coincidence with the centerof the outlet pipe connecting opening.

If the projection is so positioned as stated above, the refrigerantoutlet portion exhibits an improved effect to smooth the flow ofrefrigerant due to the presence of the projection, reliably preventingthe occurrence of noises.

With the first evaporator of the invention, the refrigerant flowsmoothing projection is not specifically limited in shape insofar as therefrigerant flowing into the inlet channel or flowing out of the outletchannel can be prevented from flowing unevenly or turbulently. Theprojection is, for example, substantially conical, frustoconical orsemispherical.

If the projection is substantially conical, frustoconical orsemispherical, the refrigerant can change its course smoothly by flowingalong the surface of the projection and is less likely to becometurbulent.

With the first evaporator of the invention, the evaporator core is notparticularly limited in construction insofar as the refrigerant inletand the refrigerant outlet can be provided in one side portion thereof.Stated more specifically, the evaporator core comprises upper and lowertwo horizontal headers, and a plurality of vertical heat exchange tubesarranged laterally at a spacing and each having opposite endscommunicating with the upper and lower headers respectively, therefrigerant inlet being provided at one end of one of the upper andlower headers, the refrigerant outlet being provided at one end of theother header.

The evaporator core described above may be of the layered type whichcomprises a multiplicity of core plates each having an upper and a lowerheader recessed portion, and a tube recessed portion having oppositeends integral with the respective header recessed portions and shallowerthan the header recessed portions, and which is fabricated by joiningeach pair of these core plates to each other with each pair ofcorresponding recessed portions opposed to each other.

The present invention further provides a first refrigeration cycle whichcomprises the first evaporator described.

The noise to be produced by the flow of refrigerant in the evaporator ofthis refrigeration cycle is prevented by the refrigerant flow smoothingprojection provided in the evaporator itself. This realizes a silentoperation without necessitating an additional cost or additionalinstallation space since there is no need to incorporate a specialdevice at a position upstream from the evaporator as practicedconventionally. The invention is advantageously applicable especially tomotor vehicle air conditioners.

The present invention provides a second evaporator which comprises anevaporator core having a refrigerant inlet and a refrigerant outlet inone side portion thereof, and a connecting member joined to said oneside portion of the evaporator core and having in its interior arefrigerant inlet channel for holding the refrigerant inlet incommunication with a refrigerant inlet pipe and a refrigerant outletchannel for holding the refrigerant outlet in communication with arefrigerant outlet pipe. The connecting member comprises a first platehaving an inlet communication hole and an outlet communication hole andjoined to said one side portion of the evaporator core so that thecommunication holes communicate with the respective refrigerant inletand outlet, and a second plate having an inlet channel recessed portionand an outlet channel recessed portion and joined to an outer surface ofthe first plate so that the recessed portions are opposed each at oneend thereof to the inlet communication hole and the outlet communicationhole respectively. A multi-pass providing inner pipe is inserted in theevaporator core through the inlet communication hole and the refrigerantinlet and provided at a base end thereof with a flange joined to aninner periphery of the first plate defining the inlet communicationhole. The other end of the inlet channel recessed portion has a bottomwall provided with an inlet pipe connecting opening, the other end ofthe outlet channel recessed portion having a bottom wall provided withan outlet pipe connecting opening, the refrigerant inlet pipe and therefrigerant outlet pipe being connectable to the respective connectingopenings by a pipe joint member joined to an outer surface of the secondplate. The refrigerant inlet channel is divided into at least twoparallel inlet branch channels in the vicinity of the inlet pipeconnecting opening, the inlet branch channels being combined together inthe vicinity of the inlet communication hole.

A refrigerant subjected to a pressure reduction by an expansion valveand in a gas-liquid two-phase state flows into the refrigerant inletchannel of the connecting member of the evaporator through a refrigerantinlet pipe and the pipe joint member and further through the inlet pipeconnecting opening. The refrigerant flowing in dividedly flows throughat least two inlet branch channels in the same direction, the dividedrefrigerant portions combine together again in the vicinity of the inletcommunication hole, and the confluent refrigerant thereafter flows intothe inner pipe. The pressure loss of the refrigerant flowing into theinner pipe is smaller than when the refrigerant inlet channel is notbranched, permitting the refrigerant to flow into the inner pipesmoothly. The second evaporator described therefore enables therefrigerant to flow into the evaporator core efficiently, consequentlyexhibiting improved air cooling performance.

The second evaporator according to the invention also has the followingadvantage. When the refrigerant inlet channel is divided into at leasttwo branch channels, the recessed portions to be formed in the secondplate for providing these branch channels can be made smaller in width,while the flat portion to be joined to the first plate is given anincreased area. Accordingly, a sufficient pressure resistant strength isavailable against the flow of refrigerant even if a material of reducedthickness is used for the second plate, hence a corresponding costreduction.

With the second evaporator of the invention, it is desired that therefrigerant outlet channel be also divided into at least two paralleloutlet branch channels in the vicinity of the outlet communication hole,the outlet branch channels being combined together in the vicinity ofthe outlet pipe connecting opening.

If the refrigerant outlet channel is also divided into at least twobranch channels, the recessed portions to be formed in the second platefor providing these branch channels can be made smaller in width, whilethe flat portion to be joined to the first plate is given an increasedarea. The second plate can then be further smaller in thickness.

In the second evaporator according to the invention, the first plate isprovided in the outer surface thereof with an inlet recessed portion andan outlet recessed portion at portions thereof corresponding to therefrigerant inlet and the refrigerant outlet respectively, and the inletcommunication hole is formed in a bottom wall of the inlet recessedportion. These two recessed portions are provided to form a clearancefor the air to be cooled to pass therethrough between the evaporatorcore and the connecting member. In this case, it is desired that a partof the flange of the inner pipe preferably be opposed to a flat portionof the second plate, and that the remaining part of the flange beopposed to a bottom wall of one end of the inlet channel recessedportion of the second plate.

The flange of the inner pipe is joined to an inner peripheral portion ofthe first plate defining the inlet communication hole. Especially whenthe evaporator is used as such in a motor vehicle air conditioner, theinner pipe flange could inevitably slip off the hole-defining peripheralportion. In the event of such a situation occurring, the inner pipeslipping off the first plate will shift outward, permitting the flangein its entirety to come into contact with the bottom wall of one end ofthe inlet channel recessed portion of the second plate. This impedes theflow of refrigerant into the inner pipe or permits the refrigerant toflow into the pipe intermittently, impairing the function of theevaporator and rendering the motor vehicle air conditioner or likerefrigeration cycle itself no longer serviceable as such. Accordingly, apart of the flange is positioned as opposed to the flat portion of thesecond plate as described above. Even if the inner pipe then inevitablyslips off the first plate and shifts outward, with the flange partlybrought into contact with the flat portion of the second plate, aclearance sufficient for the refrigerant to flow into the inner pipetherethrough will be created between the remaining part of the flangeand the bottom wall of one end of the inlet channel recessed portion ofthe second plate. Consequently, the function of the evaporator will notbe substantially impaired even in the event of the above situationoccurring, and the motor vehicle air conditioner or like refrigerationcycle can be used continuously.

In the above-mentioned case, the flat portion of the second plateopposed to said part of the flange of the inner pipe is, for example,one end of a striplike flat portion provided at a position intermediatethe width of the inlet channel recessed portion for dividing therefrigerant inlet channel into at least two branch channels. If the flatportion around the inlet channel recessed portion of the second platehas a sufficient width, the flange of the inner pipe may partly beopposed to this flat portion.

The present invention further provides a third evaporator whichcomprises an evaporator core having a refrigerant inlet and arefrigerant outlet in one side portion thereof, and a connecting memberjoined to said one side portion of the evaporator core and having in itsinterior a refrigerant inlet channel for holding the refrigerant inletin communication with a refrigerant inlet pipe and a refrigerant outletchannel for holding the refrigerant outlet in communication with arefrigerant outlet pipe. The connecting member comprises a first platehaving an inlet communication hole and an outlet communication hole andjoined to said one side portion of the evaporator core so that thecommunication holes communicate with the respective refrigerant inletand outlet, and a second plate having an inlet channel recessed portionand an outlet channel recessed portion and joined to an outer surface ofthe first plate so that the recessed portions are opposed each at oneend thereof to the inlet communication hole and the outlet communicationhole respectively. A multi-pass providing inner pipe is inserted in theevaporator core through the outlet communication hole and therefrigerant outlet and provided at a base end thereof with a flangejoined to an inner periphery of the first plate defining the outletcommunication hole. The other end of the inlet channel recessed portionhas a bottom wall provided with an inlet pipe connecting opening, theother end of the outlet channel recessed portion having a bottom wallprovided with an outlet pipe connecting opening, the refrigerant inletpipe and the refrigerant outlet pipe being connectable to the respectiveconnecting openings by a pipe joint member joined to an outer surface ofthe second plate. The refrigerant outlet channel is divided into atleast two parallel outlet branch channels in the vicinity of the outletcommunication hole, the outlet branch channels being combined togetherin the vicinity of the outlet pipe connecting opening.

The refrigerant flowing through the evaporator core then flows throughthe inner pipe and further flows out of the refrigerant outlet into therefrigerant outlet channel of the connecting member. The refrigerantsubsequently dividedly flows through the two or more outlet branchchannels in the same direction, the divided refrigerant portions combinetogether again in the vicinity of the outlet pipe connecting opening,and the confluent flow is thereafter discharged from this opening intothe refrigerant outlet pipe via the pipe joint member. The pressure lossof the refrigerant flowing out of the inner pipe is smaller than whenthe refrigerant outlet channel is not branched, and the refrigerantsmoothly flows out of the inner pipe. Thus, the third evaporator enablesthe refrigerant to flow out of the evaporator core efficiently,consequently exhibiting improved air cooling performance.

In the case of the third evaporator of the invention, the refrigerantoutlet channel is divided into at least two branch channels, so thateven if the second plate is made from a material of reduced thickness, asufficient pressure resistant strength is available against the flow ofrefrigerant to realize a cost reduction.

In the third evaporator of the invention, the refrigerant inlet channelis also preferably divided into at least two parallel inlet branchchannels in the vicinity of the inlet pipe connecting opening, the inletbranch channels being combined together in the vicinity of the inletcommunication hole.

If the refrigerant inlet channel is divided into at least two branchchannels, the second plate can be made further smaller in thickness.

In the case where the first plate is provided in the outer surfacethereof with an inlet recessed portion and an outlet recessed portion atportions thereof corresponding to the refrigerant inlet and therefrigerant outlet, respectively, in the third evaporator of theinvention, with the outlet communication hole formed in a bottom wall ofthe outlet recessed portion, it is desired that a part of the flange ofthe inner pipe be opposed to a flat portion of the second plate, andthat the remaining part of the flange be opposed to a bottom wall of oneend of the outlet channel recessed portion of the second plate.

If the flange is partly opposed to the flat portion of the second plate,this arrangement has the following advantage. Even if the inner pipeinevitably slips off the first plate and shifts outward, with the flangepartly brought into contact with the flat portion of the second plate, aclearance sufficient for the refrigerant to flow into the inner pipetherethrough will be created between the remaining part of the flangeand the bottom wall of one end of the inlet channel recessed portion ofthe second plate. Consequently, the function of the evaporator will notbe substantially impaired even in the event of the above situationoccurring, and the motor vehicle air conditioner or like refrigerationcycle can be used continuously.

In the above case, the flat portion of the second plate opposed to saidpart of the flange of the inner pipe is, for example, one end of astriplike flat portion provided at a position intermediate the width ofthe outlet channel recessed portion for dividing the refrigerant outletchannel into at least two branch channels. If the flat portion aroundthe outlet channel recessed portion of the second plate has a sufficientwidth, the flange of the inner pipe may partly be opposed to this flatportion.

In the second or third evaporator according to the invention, the firstplate is preferably provided on the outer surface thereof with arefrigerant flow smoothing projection projecting toward at least one ofthe inlet pipe connecting opening and the outlet pipe connecting openingof the second plate.

The projection then affords the same advantage as the first evaporator.The flow smoothing projection projecting toward the inlet pipeconnecting opening serves to more smoothly divide the refrigerant intothe portions to be passed through the branch channels. The flowsmoothing projection projecting toward the outlet pipe connectingopening serves to more smoothly combine the divided refrigerant portionsfrom the outlet branch channels.

With the second or third evaporator of the invention, the evaporatorcore is not particularly limited in construction insofar as therefrigerant inlet and the refrigerant outlet can be provided in one sideportion thereof. Stated more specifically, the evaporator core comprisesupper and lower two horizontal headers, and a plurality of vertical heatexchange tubes arranged laterally at a spacing and each having oppositeends communicating with the upper and lower headers respectively, therefrigerant inlet being provided at one end of one of the upper andlower headers, the refrigerant outlet being provided at one end of theother header.

The evaporator core described above may be of the layered type whichcomprises a multiplicity of core plates each having an upper and a lowerheader recessed portion, and a tube recessed portion having oppositeends integral with the respective header recessed portions and shallowerthan the header recessed portions, and which is fabricated by joiningeach pair of these core plates to each other with each pair ofcorresponding recessed portions opposed to each other.

The present invention further provides a second refrigeration cyclewhich comprises the second or third evaporator described.

The refrigeration cycle attains outstanding air cooling performancesince a reduction is achieved in the pressure loss to be involved inintroducing the refrigerant into the multi-pass providing inner pipeinstalled within the evaporator or in discharging the refrigerant fromthe inner pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of an embodiment of the invention, i.e., anevaporator.

FIG. 2 is a bottom view of the evaporator.

FIG. 3 is a view in horizontal section of a heat exchange tube in anevaporator core of the evaporator.

FIG. 4 shows a connecting member, pipe joint member and multi-pass innerpipe, (a) being a side elevation, (b) being a view in vertical section.

FIG. 5 is a perspective view showing the connecting member, pipe jointmember and multi-pass inner pipe as disassembled.

FIG. 6 shows a part of the evaporator core including a lower header, (a)being a view in horizontal section, (b) being a view in verticalsection.

FIG. 7 is a diagram showing the flow of refrigerant within theevaporator.

BEST MODE OF CARRYING OUT THE INVENTION

Next, the preferred embodiment of the invention will be described withreference to FIGS. 1 to 7. In the following description, the upper,lower, left-hand and right-hand sides of FIG. 1 will be referred to as“upper,” “lower,” “left” and “right,” respectively, and the upper sideof FIG. 2 will be referred to as “front,” and the lower side of FIG. 2as “rear.”

The embodiment is a layered evaporator embodying the present inventionfor use in motor vehicle air conditioners. With reference to FIGS. 1 and2, the evaporator 1 of the invention comprises an evaporator core 2, anda connecting member 3 joined to the right side of the core 2. A pipejoint member 4 is joined to a right side portion of the connectingmember 3. The evaporator 1 of this embodiment is made of aluminum(including an aluminum alloy), and brazing is usually resorted to forjoining the components of the evaporator to be described below.

The evaporator core 2 comprises upper and lower two horizontal headers21, 22, and a plurality of vertical heat exchange tubes 23 arrangedlaterally at a spacing and each having opposite ends communicating withthe upper and lower headers 21, 22, respectively. A refrigerant inlet 2Ais provided at the right end of the lower header 22, and a refrigerantoutlet 2B at the right end of the upper header 21 (see FIG. 7).

The evaporator core 2 comprises a multiplicity of core plates 20 eachhaving upper and lower header recessed portions 201, 202, and a tuberecessed portion 203 integral with the recessed portions 201, 202 at itsopposite ends and shallower than these recessed portions 201, 202, andis fabricated by joining each pair of these core plates 20 to each otherwith each pair of corresponding recessed portions 201, 202 or 203opposed to each other. A multi-pass providing inner pipe 5 is insertedin the lower header 22 through the refrigerant inlet 2A thereof as seenin FIG. 2.

With reference to FIGS. 1 and 2, a side plate 6 is provided at the leftend of the evaporator core 2. The side plate 6 has at its upper andlower ends recessed portions 61, 62 of the same shape and size as theheader recesses 201, 202. The bottom walls of these recessed portions61, 62 are joined to the respective bottom walls of the upper and lowerheader recessed portions 201, 202 of the core plate 20 positioned at theleft end.

As shown in FIG. 1, an outer fin 7 is fixedly provided in each of aclearance between each pair of adjacent heat exchange tubes 23, aclearance between the heat exchanger tube 23 at the left end and theside plate 6, and a clearance between the heat exchange tube 23 at theright end and the connecting member 3. The outer fin 7 is, for example,in the form of a corrugated fin as shown in FIG. 1. The air A to becooled is passed through the clearances from the rear forward as shownin FIG. 2.

FIG. 3 shows the heat exchange tube 23 of the evaporator core 2. Thetube recessed portion 203 of the core plate 20 is divided into front andrear two parts by a partition ridge 204 formed at the midportion of thewidth of the portion 203. Accordingly, the interior of the heat exchangetube 23 is also partitioned into front and rear two parts. Therefrigerant flows through the front and rear parts of interior of thetube 23 in the same direction in parallel, and the two refrigerantportions will join at the upper or lower header 21 or 22. An inner fin 8is enclosed in each of the front and rear parts of the tube 23. Theinner fin 8 comprises, for example, a corrugated fin as seen in FIG. 3.Of course, the heat exchange tube is not always divided into front andrear parts as seen in FIG. 3.

FIGS. 4 and 5 show the connecting member 3 along with the pipe jointmember 4 and the inner pipe 5. The connecting member 3 has in itsinterior a refrigerant inlet channel 3A for holding the refrigerantinlet 2A in communication with a refrigerant inlet pipe (not shown) anda refrigerant outlet channel 3B for holding the refrigerant outlet 2B incommunication with a refrigerant outlet pipe (not shown). The connectingmember 3 comprises a first plate 31 and a second plate 32.

The first plate 31 has an inlet communication hole 31A in a lower endportion thereof, and an outlet communication hole 31B in an upper endportion thereof. The plate 31 is joined to the right side of theevaporator core 2 so that these holes 31A, 31B communicate with therefrigerant inlet 2A and outlet 2B, respectively. The portion of thefirst plate 31 corresponding to the inlet 2A, i.e., the lower endportion, is provided with an inlet recessed portion 311. The portion ofthe first plate 31 corresponding to the outlet 2B, i.e., the upper endportion, is provided with an outlet recessed portion 312. These recessedportions 311, 312 are the same as the upper and lower header recessedportions 201, 202 of the core plate 20 in shape and size. The bottomwalls of these recessed portions 311, 312 are joined to the bottom wallsof upper and lower header recessed portions 201, 202 of the core plate20 positioned at the right end. The inlet communication hole 31A isformed in the center of bottom wall of the inlet recessed portion 311,is circular and has a diameter approximately equal to the outsidediameter of the inner pipe 5. The outlet communication hole 31B isformed in the bottom wall of the outlet recessed portion 312, issubstantially similar to the bottom wall in shape and is elongatedforward or rearward. A vertically elongated cutout 313 is formed in eachof the front and rear edges of the first plate 31 at an intermediateportion of the height thereof.

The second plate 32 has a channel recessed portion 32A at a lowerportion thereof for forming the refrigerant inlet channel and a channelrecessed portion 32B at an upper portion thereof for forming therefrigerant outlet channel. The second plate 32 is joined to the outersurface of the first plate 31 so that the lower end of the channelrecessed portion 32A is opposed to the inlet communication hole 31A,with the upper end of the channel recessed portion 32B opposed to theoutlet communication hole 31B. The upper end of the inlet channelrecessed portion 32A has a bottom wall provided with an opening 321 forconnecting the refrigerant inlet pipe. The lower end of the outletchannel recessed portion 32B has a bottom wall provided with an opening322 for connecting the refrigerant outlet pipe. These connectingopenings 321, 322 are circular. The peripheral edges of these openings321, 322 are projected outward. The front and rear edges of the secondplate 32 each have an inwardly bent portion 323 at an intermediateportion of the height thereof. With the first and second plates 31, 32fitted to each other, the bent portion 323 fits in the cutout 313 (seeFIG. 1).

The first plate 31 is provided on the outer surface thereof with upperand lower two projections 310A, 310B projecting toward the inlet pipeconnecting opening 321 and the outlet pipe connecting opening 322,respectively, for smoothing the flow of refrigerant.

The center of the lower projection 310A is in coincidence with thecenter of the inlet pipe connecting opening 321. The center of the upperprojection 310B coincides with the center of the outlet pipe connectingopening 322.

As shown in FIG. 4, the refrigerant flow smoothing projections 310A,310B are each substantially frustoconical cone. Alternatively, theseprojections may be substantially conical or semispherical.

The refrigerant inlet channel 3A inside the connecting member 3 isdivided into two parallel inlet branch channels 30A in the vicinity ofthe inlet pipe connecting opening 321, and the branch channels 30A arecombined together in the vicinity of the inlet communication hole 31A.Further the refrigerant outlet channel 3B is also divided into twoparallel outlet branch channels 30B in the vicinity of the outletcommunication hole 31B, and the branch channels 30B are combinedtogether in the vicinity of the outlet pipe connecting opening 322. Whenthe refrigerant inlet channel 3A and the outlet channel 3B are eachdivided into two branch channels 30A or 30B as described above, therecessed portions 32A, 32B provided in the second plate 32 for formingthese channels can be smaller in width, while the flat portion 324 ofthe second plate 32 to be joined to the first plate 31 is given anincreased area. This affords a sufficient pressure resistant strengthagainst the flow of refrigerant even if a material of reduced thicknessis used for the second plate 32.

The pipe joint member 4 is in the form of a block having upper and lowertwo bores 41, 42 extending laterally through the thickness thereof. Thejoint member 4 is joined to the outer surface of the second plate 32,with the inner end of the lower bore 41 in coincidence with the inletpipe connecting opening 321, and with the inner end of the upper bore 42coinciding with the outlet pipe connecting opening 322. The outer end ofthe lower bore 41 is provided with an outwardly projecting socket 4A forinserting the refrigerant inlet pipe thereinto for connection. The outerend of the upper bore 42 is provided with an outwardly projecting socket4B for inserting the refrigerant outlet pipe thereinto for connection.An O-ring 9 is fitted around the base end of each of the sockets 4A, 4B.

The multi-pass providing inner pipe 5 is provided at the base endthereof with an annular flange 51 integrally therewith. The flange 51 ofthe inner pipe 5 is joined to an inner peripheral edge of the firstplate 31 defining the inlet communication hole 31A. The flange 51 isjoined to the hole-defining peripheral edge usually by tacking thesejoint portions by crimping and subsequent brazing.

With reference to FIG. 4, a part of the flange 51 of the inner pipe 5 isopposed to the flat portion 324 of the second plate 32, morespecifically, to the lower end of the striplike flat portion 324 whichis formed at the widthwise midportion of the inlet channel recessedportion 32A for dividing the refrigerant inlet channel 3A into the twobranch channels, and the remaining part of the flange 51 is opposed tothe lower end of the inlet channel recessed portion 32A of the secondplate 32. Although the flange 51 is firmly joined to the innerperipheral edge of the first plate 31 defining the inlet communicationhole 31A by brazing as described above, the flange 51 of the inner pipe5 could inevitably slip off the hole-defining edge. In the event of sucha situation occurring, the inner pipe 5 slipping off from the firstplate 31 shifts rightward, with the result that the flange 51 thereof inits entirety comes into contact with the bottom wall of lower end of theinlet channel recessed portion 32A of the second plate 32. This impedesthe flow of refrigerant into the inner pipe 5 or permits the refrigerantto flow into the pipe intermittently, impairing the function of theevaporator 1 and consequently rendering the motor vehicle airconditioner itself no longer serviceable as such. On the other hand, theflange 51 is partly opposed to the flat portion 324 of the second plate32 as shown in FIG. 4. If the inner pipe 5 then inevitably slips off thefirst plate 31 and shifts rightward, the flange 51 will partly come intocontact with the flat portion 324 of the second plate 32. However, aclearance sufficient for the refrigerant to flow into the inner pipe 5therethrough will be created between the remaining part of the flange 51and the bottom wall of lower end of the inlet channel recessed portion32A of the second plate 32. Accordingly, the function of the evaporator1 will not be substantially impaired even in the event of the abovesituation occurring, and the motor vehicle air conditioner can be usedcontinuously.

FIG. 6 shows a part of the evaporator core 2 including the lower header22. The inner pipe 5 is inserted in the lower header 22 of theevaporator core 2 through the inlet communication hole 31A and therefrigerant inlet 2A. The forward end (left end) of the inner pipe 5 ispositioned at a distance of about ⅔ of the length of the lower header 22from the right end of the lower header 22 as seen in FIG. 2.

With reference to FIG. 6, the bottom walls of the lower header recessedportions 202 of core plates 20 are each provided with a hole 202A. Thehole 202A has a shape elongated forward or rearward and substantiallysimilar to that of the bottom wall of the recessed portion 202.Accordingly, clearances permitting the passage of the refrigeranttherethrough are formed around the inner pipe 5 in the hole 202A [seeFIG. 6(a)]. However, the hole 202X formed in the bottom wall of recessedportion 202 of each of the two core plates 20 positioned close to theforward end of the inner pipe 5 is small and circular and has a diameterapproximately equal to the outside diameter of the inner pipe 5, so thatno clearance is formed around the pipe 5 in the hole 202X. In otherwords, the bottom walls of the lower header recessed portions 202 havingthe hole 202X provide a partition wall 221 for dividing the interior ofthe lower header 22 into left and right sections (see FIGS. 6 and 7).

Although not shown, the bottom walls of the upper header recessedportions 201 of core plates 20 are also each provided with the same holeas the hole 202A in the lower header recessed portion 202. However, thehole is not formed in the bottom wall of upper header recessed portion201 of the core plate 20 which is positioned at a distance of about ⅓ ofthe entire length of the evaporator core 2 from the right end of thecore 2. This bottom wall provides a partition wall 211 dividing theupper header 21 into left and right sections (see FIG. 7). The twopartition walls 211, 221 and the inner pipe 5 thus provided within theevaporator core 2 form a plurality of passes in the core 2. Stated morespecifically, a first pass P1 is provided by the heat exchange tubes 23positioned in a left portion of the evaporator core 2 and having lowerends communicating with the left section 22L of the lower header 22 andupper ends communicating with the left section 21L of the upper header21. A second pass P2 is provided by the heat exchange tubes 23positioned in a central portion of the evaporator core 2 and havingupper ends communicating with the left section 21L of the upper header21 and lower ends communicating with the right section 22R of the lowerheader 22. A third pass P3 is provided by the heat exchange tubes 23positioned in a right portion of the evaporator core 2 and having lowerends communicating with the right section 22R of the lower header 22 andupper ends communicating with the right section 21R of the upper header21.

With reference to FIG. 6, the distance X between the left end of theinner pipe 5 and the partition wall 221 is greater than the distance Ybetween the flange 51 at the base end of the inner pipe 51 and the flatportion 324 of the second plate 32. When the inner pipe 5 slips off thefirst plate 31 and shifts rightward as stated above, the left end of thepipe 5 of course also shifts rightward. If the distance X between theleft end of the inner pipe 5 and the partition wall 221 is then smallerthan the distance Y between the flange 51 and the flat portion 324, therefrigerant flowing inside the pipe 5 toward the left end thereof willbe admitted into the section 22R of the lower header 22 on the rightside of the partition wall 221 thereof instead of flowing along thecontemplated refrigerant circuit in the evaporator core 2. This entailsthe likelihood that a sufficient air cooling effect will not beavailable. On the other hand, if the distance X between the left end ofthe inner pipe 5 and the partition wall 221 is greater than the distanceY between the flange 51 and the flat portion 324 as shown in FIG. 6, therefrigerant flowing through the inner pipe 5 is admitted into thesection 22L of the lower header 22 on the left side of the partitionwall 221 even if the pipe 5 shifts rightward upon slipping off. Therefrigerant therefore flows normally through the evaporator core 3 toproduce the desired cooling effect.

FIG. 7 shows the flow of refrigerant inside the evaporator 1. Althoughnot shown, the motor vehicle air conditioner comprises a refrigerationcycle including a compressor, condenser and expansion valve, in additionto the evaporator 1 described.

The refrigerant, as subjected to a pressure reduction by an expansionvalve and in a gas-liquid two-phase state, first flows into the inletpipe connecting opening 321 by way of the refrigerant inlet pipe and thelower bore 41 of the pipe joint member 4 and then into the refrigerantinlet channel 3A of the connecting member 3.

The refrigerant flowing in impinges on the outer surface of the firstplate 31 opposed to the inlet pipe connecting opening 321, has itscourse thereby changed approximately through a right angle to flowthrough the inlet channel 3A and thereafter flows into the evaporatorcore 2 from the refrigerant inlet 2A. At this time, the refrigerantflowing into the inlet channel 3A flows along the surface of the lowerrefrigerant flow smoothing projection 310A formed on the outer surfaceof the first plate 31 and opposed to the inlet pipe connecting opening321. This smoothly changes the direction of the flow, further reducingthe likelihood of the flow becoming turbulent. Consequently, theprojection 310A eliminates the noise to be produced by the inflow of therefrigerant.

Subsequently, the refrigerant dividedly flows down the two inlet branchchannels 30A, the divided refrigerant portions combine together again inthe vicinity of the inlet communication hole 31A, and the confluentrefrigerant thereafter flows into the inner pipe 5 through the base endthereof. The refrigerant inlet channel 3A mentioned above is divided, inthe vicinity of the inlet pipe connecting opening 321, into the twobranch channels 30A, which are combined in the vicinity of the inletcommunication hole 31A, so that the pressure loss of the refrigerantflowing into the inner pipe 5 is smaller than when the refrigerant inletchannel is not branched. The refrigerant therefore smoothly flows intothe inner pipe 5. Accordingly, the refrigerant flows into the evaporatorcore 2 efficiently to achieve an improved heat exchange efficiency.

The refrigerant flowing through the inner pipe 5 flows into the leftsection 22L of the lower header 22 in the evaporator core 2. From thissection, the refrigerant flows up the heat exchange tubes 23constituting the first pass P1 and reaches the left section 21L of theupper header 21. The refrigerant then flows down the heat exchange tubes23 constituting the second pass P2 to reach the right section 22R of thelower header 22. The refrigerant further flows up the heat exchangetubes 23 providing the third pass P3 and reaches the right section 21Rof the upper header 21.

The refrigerant flows through the right section 21R of the upper header21 and flows into the refrigerant outlet channel 3B of the connectingmember 3 via the refrigerant outlet 2B. The refrigerant flowing in thendividedly flows down the two outlet branch channels 30B, the dividedrefrigerant portions combine together again in the vicinity of theoutlet pipe connecting opening 322, and the confluent refrigerantthereafter flows through the opening 322 and through the upper bore 42of the pipe joint member 4 into the refrigerant outlet pipe. Therefrigerant flowing out of the outlet channel 3B at this time flowsalong the surface of the upper refrigerant flow smoothing projection310B formed on the outer surface of the first plate 31 and opposed tothe outlet pipe connecting opening 322. This smoothly changes thedirection of the flow, further reducing the likelihood of the flowbecoming turbulent. Consequently, the projection 310B eliminates thenoise to be produced by the outflow of the refrigerant.

The foregoing embodiment is given for illustrative purpose only, and thepresent invention can of course be practiced by modifying the embodimentsuitably within the scope of the invention as set forth in the appendedclaims.

1. An evaporator comprising an evaporator core having a refrigerantinlet and a refrigerant outlet in one side portion thereof, and aconnecting member joined to said one side portion of the evaporator coreand having in its interior a refrigerant inlet channel for holding therefrigerant inlet in communication with a refrigerant inlet pipe and arefrigerant outlet channel for holding the refrigerant outlet incommunication with a refrigerant outlet pipe, the connecting membercomprising a first plate having an inlet communication hole and anoutlet communication hole and joined to said one side portion of theevaporator core so that the communication holes communicate with therespective refrigerant inlet and outlet, and a second plate having aninlet channel recessed portion and an outlet channel recessed portionand joined to an outer surface of the first plate so that the recessedportions are opposed each at one end thereof to the inlet communicationhole and the outlet communication hole respectively, the other end ofthe inlet channel recessed portion having a bottom wall provided with aninlet pipe connecting opening, the other end of the outlet channelrecessed portion having a bottom wall provided with an outlet pipeconnecting opening, the refrigerant inlet pipe and the refrigerantoutlet pipe being connectable to the respective connecting openings by apipe joint member joined to an outer surface of the second plate, thefirst plate being provided on the outer surface thereof with arefrigerant flow smoothing projection projecting toward the inlet pipeconnecting opening of the second plate.
 2. An evaporator according toclaim 1 wherein the refrigerant flow smoothing projection has a centercoinciding with a center of the inlet pipe connecting opening.
 3. Anevaporator comprising an evaporator core having a refrigerant inlet anda refrigerant outlet in one side portion thereof, and a connectingmember joined to said one side portion of the evaporator core and havingin its interior a refrigerant inlet channel for holding the refrigerantinlet in communication with a refrigerant inlet pipe and a refrigerantoutlet channel for holding the refrigerant outlet in communication witha refrigerant outlet pipe, the connecting member comprising a firstplate having an inlet communication hole and an outlet communicationhole and joined to said one side portion of the evaporator core so thatthe communication holes communicate with the respective refrigerantinlet and outlet, and a second plate having an inlet channel recessedportion and an outlet channel recessed portion and joined to an outersurface of the first plate so that the recessed portions are opposedeach at one end thereof to the inlet communication hole and the outletcommunication hole respectively, the other end of the inlet channelrecessed portion having a bottom wall provided with an inlet pipeconnecting opening, the other end of the outlet channel recessed portionhaving a bottom wall provided with an outlet pipe connecting opening,the refrigerant inlet pipe and the refrigerant outlet pipe beingconnectable to the respective connecting openings by a pipe joint memberjoined to an outer surface of the second plate, the first plate beingprovided on the outer surface thereof with a refrigerant flow smoothingprojection projecting toward the outlet pipe connecting opening of thesecond plate.
 4. An evaporator according to claim 3 wherein therefrigerant flow smoothing projection has a center coinciding with acenter of the outlet pipe connecting opening.
 5. An evaporatorcomprising an evaporator core having a refrigerant inlet and arefrigerant outlet in one side portion thereof, and a connecting memberjoined to said one side portion of the evaporator core and having in itsinterior a refrigerant inlet channel for holding the refrigerant inletin communication with a refrigerant inlet pipe and a refrigerant outletchannel for holding the refrigerant outlet in communication with arefrigerant outlet pipe, the connecting member comprising a first platehaving an inlet communication hole and an outlet communication hole andjoined to said one side portion of the evaporator core so that thecommunication holes communicate with the respective refrigerant inletand outlet, and a second plate having an inlet channel recessed portionand an outlet channel recessed portion and joined to an outer surface ofthe first plate so that the recessed portions are opposed each at oneend thereof to the inlet communication hole and the outlet communicationhole respectively, the other end of the inlet channel recessed portionhaving a bottom wall provided with an inlet pipe connecting opening, theother end of the outlet channel recessed portion having a bottom wallprovided with an outlet pipe connecting opening, the refrigerant inletpipe and the refrigerant outlet pipe being connectable to the respectiveconnecting openings by a pipe joint member joined to an outer surface ofthe second plate, the first plate being provided on the outer surfacethereof with two refrigerant flow smoothing projections projectingrespectively toward the inlet pipe connecting opening and the outletpipe connecting opening of the second plate.
 6. An evaporator accordingto claim 5 wherein centers of the two refrigerant flow smoothingprojections are in coincidence with respective centers of the inlet pipeconnecting opening and the outlet pipe connecting opening.
 7. Anevaporator according to claim 1 wherein the refrigerant flow smoothingprojection or projections are substantially conical.
 8. An evaporatoraccording to claim 1 wherein the refrigerant flow smoothing projectionor projections are substantially frustoconical.
 9. An evaporatoraccording to claim 1 wherein the refrigerant flow smoothing projectionor projections are substantially semispherical.
 10. An evaporatoraccording to claim 1 wherein the evaporator core comprises upper andlower two horizontal headers, and a plurality of vertical heat exchangetubes arranged laterally at a spacing and each having opposite endscommunicating with the upper and lower headers respectively, therefrigerant inlet being provided at one end of one of the upper andlower headers, the refrigerant outlet being provided at one end of theother header.
 11. An evaporator according to claim 10 wherein theevaporator core comprises a multiplicity of core plates each having anupper and a lower header recessed portion, and a tube recessed portionhaving opposite ends integral with the respective header recessedportions and shallower than the header recessed portions, and isfabricated by joining each pair of these core plates to each other witheach pair of corresponding recessed portions opposed to each other. 12.A refrigeration cycle comprising an evaporator according to claim
 1. 13.An evaporator comprising an evaporator core having a refrigerant inletand a refrigerant outlet in one side portion thereof, and a connectingmember joined to said one side portion of the evaporator core and havingin its interior a refrigerant inlet channel for holding the refrigerantinlet in communication with a refrigerant inlet pipe and a refrigerantoutlet channel for holding the refrigerant outlet in communication witha refrigerant outlet pipe, the connecting member comprising a firstplate having an inlet communication hole and an outlet communicationhole and joined to said one side portion of the evaporator core so thatthe communication holes communicate with the respective refrigerantinlet and outlet, and a second plate having an inlet channel recessedportion and an outlet channel recessed portion and joined to an outersurface of the first plate so that the recessed portions are opposedeach at one end thereof to the inlet communication hole and the outletcommunication hole respectively, a multi-pass providing inner pipe beinginserted in the evaporator core through the inlet communication hole andthe refrigerant inlet and being provided at a base end thereof with aflange joined to an inner periphery of the first plate defining theinlet communication hole, the other end of the inlet channel recessedportion having a bottom wall provided with an inlet pipe connectingopening, the other end of the outlet channel recessed portion having abottom wall provided with an outlet pipe connecting opening, therefrigerant inlet pipe and the refrigerant outlet pipe being connectableto the respective connecting openings by a pipe joint member joined toan outer surface of the second plate, the refrigerant inlet channelbeing divided into at least two parallel inlet branch channels in thevicinity of the inlet pipe connecting opening, the inlet branch channelsbeing combined together in the vicinity of the inlet communication hole.14. An evaporator according to claim 13 wherein the refrigerant outletchannel is divided into at least two parallel outlet branch channels inthe vicinity of the outlet communication hole, the outlet branchchannels being combined together in the vicinity of the outlet pipeconnecting opening.
 15. An evaporator according to claim 13 wherein thefirst plate is provided in the outer surface thereof with an inletrecessed portion and an outlet recessed portion at portions thereofcorresponding to the refrigerant inlet and the refrigerant outletrespectively, and the inlet communication hole is formed in a bottomwall of the inlet recessed portion, a part of the flange of the innerpipe being opposed to a flat portion of the second plate, the remainingpart of the flange being opposed to a bottom wall of one end of theinlet channel recessed portion of the second plate.
 16. An evaporatoraccording to claim 15 wherein the flat portion of the second plateopposed to said part of the flange of the inner pipe is one end portionof a striplike flat part provided at a position intermediate the widthof the inlet channel recessed portion for dividing the refrigerant inletchannel into at least two branch channels.
 17. An evaporator comprisingan evaporator core having a refrigerant inlet and a refrigerant outletin one side portion thereof, and a connecting member joined to said oneside portion of the evaporator core and having in its interior arefrigerant inlet channel for holding the refrigerant inlet incommunication with a refrigerant inlet pipe and a refrigerant outletchannel for holding the refrigerant outlet in communication with arefrigerant outlet pipe, the connecting member comprising a first platehaving an inlet communication hole and an outlet communication hole andjoined to said one side portion of the evaporator core so that thecommunication holes communicate with the respective refrigerant inletand outlet, and a second plate having an inlet channel recessed portionand an outlet channel recessed portion and joined to an outer surface ofthe first plate so that the recessed portions are opposed each at oneend thereof to the inlet communication hole and the outlet communicationhole respectively, a multi-pass providing inner pipe being inserted inthe evaporator core through the outlet communication hole and therefrigerant outlet and being provided at a base end thereof with aflange joined to an inner periphery of the first plate defining theoutlet communication hole, the other end of the inlet channel recessedportion having a bottom wall provided with an inlet pipe connectingopening, the other end of the outlet channel recessed portion having abottom wall provided with an outlet pipe connecting opening, therefrigerant inlet pipe and the refrigerant outlet pipe being connectableto the respective connecting openings by a pipe joint member joined toan outer surface of the second plate, the refrigerant outlet channelbeing divided into at least two parallel outlet branch channels in thevicinity of the outlet communication hole, the outlet branch channelsbeing combined together in the vicinity of the outlet pipe connectingopening.
 18. An evaporator according to claim 17 wherein the refrigerantinlet channel is divided into at least two parallel inlet branchchannels in the vicinity of the inlet pipe connecting opening, the inletbranch channels being combined together in the vicinity of the inletcommunication hole.
 19. An evaporator according to claim 17 wherein thefirst plate is provided in the outer surface thereof with an inletrecessed portion and an outlet recessed portion at portions thereofcorresponding to the refrigerant inlet and the refrigerant outletrespectively, and the outlet communication hole is formed in a bottomwall of the outlet recessed portion, a part of the flange of the innerpipe being opposed to a flat portion of the second plate, the remainingpart of the flange being opposed to a bottom wall of one end of theoutlet channel recessed portion of the second plate.
 20. An evaporatoraccording to claim 19 wherein the flat portion of the second plateopposed to said part of the flange of the inner pipe is one end portionof a striplike flat part provided at a position intermediate the widthof the outlet channel recessed portion for dividing the refrigerantoutlet channel into at least two branch channels.
 21. An evaporatoraccording to claim 13 wherein the first plate is provided on the outersurface thereof with a refrigerant flow smoothing projection projectingtoward at least one of the inlet pipe connecting opening and the outletpipe connecting opening of the second plate.
 22. An evaporator accordingto claim 13 wherein the evaporator core comprises upper and lower twohorizontal headers, and a plurality of vertical heat exchange tubesarranged laterally at a spacing and each having opposite endscommunicating with the upper and lower headers respectively, therefrigerant inlet being provided at one end of one of the upper andlower headers, the refrigerant outlet being provided at one end of theother header.
 23. An evaporator according to claim 22 wherein theevaporator core comprises a multiplicity of core plates each having anupper and a lower header recessed portion, and a tube recessed portionhaving opposite ends integral with the respective header recessedportions and shallower than the header recessed portions, and isfabricated by joining each pair of these core plates to each other witheach pair of corresponding recessed portions opposed to each other. 24.A refrigeration cycle comprising an evaporator according to claim 13.